The broad objective of the proposed research is to define and validate a method suitable for the analysis of dietary fiber in hyman foodstuffs and fecal residues. Curently available methods generate fiber residues contaminated with starch and protein, depend on the use of enzymes contaminated with hemicellulases, or are unnecessarily laborious. Preliminary work suggests that starch and nitrogen-containing contaminants can be removed from neutral detergent fiber (NDF) residues of most foodstuffs by amylase and/or pancreatin pretreatment. Until the chemical nature of the fiber fractions produced by this method are known, the value of the data obtained by its use will be limited. We propose to characterize and quantify the carbohydrate hydrolysates of NDF & ADF residues and filtrates from a variety of foods by high pressure liquid chromatography. Comparison with measurements of fiber fractions obtained by accented methods of plant polysaccharide separations will further verify this method. Fecal NDF residues of samples collected from human subjects consuming rigidly controlled diets of constant composition also will be characterized by HPLC. Determination of the apparent digestibility of defined fiber fractions by human subjects is the final aim of the project.